The present invention relates generally to water-based lubricant compositions and a method of using such compositions. More particularly, the invention discloses aqueous compositions containing a long chain phosphate ester which are useful for the lubrication of continuously-moving conveyor systems, particularly conveyor systems used in the packaging of materials intended for human consumption.
Continuously-moving conveyor systems employed in food and beverage packaging operations require both cleansing and lubrication to insure that the systems function properly in moving items between packaging stations. For example, in those conveyor systems employed in bottling and capping operations, a clean and properly lubricated conveyor surface permits stoppage of the bottles during the filling and capping operations while the conveyor track continues to move underneath. If the track is not clean or does not have the proper lubricity, the containers may be knocked over or fail to stop moving, resulting both in bottle breakage and in disruption of the bottling line. These cleansing and lubricating functions are customarily accomplished by circulating an aqueous dispersion or solution of a water-based material across the track surface.
Various surface active agents have been employed as lubricants in food packaging processes, including long chain fatty acid soaps, sulfonated oils, and alkanolamides. Of particular interest to the present invention is the water-soluble agent of U.S. Pat. No. 3,574,100 which claims a track lubricant composition comprising a mixture of an imidazoline derivative and an alkali metal salt of the phosphate esters of oleyl alcohol ethoxylate.
The specific phosphate ester salt disclosed in U.S. Pat. No. 3,574,100 is a material manufactured by General Aniline and Film Corporation under the trade name, Gafac GB520. Gafac GB520 is the partial sodium salt of a mixture of mono- and di-alkyl phosphate esters derived from an oleyl alcohol polyethoxylate having eight to nine ethoxy groups, together with 35 percent of unreacted oleyl alcohol ethoxylate, i.e., EQU H.sub.3 C--(CH.sub.2).sub.7 --CH.dbd.CH--(CH.sub.2).sub.7 --CH--(O--CH.sub.2 CH.sub.2).sub.8-9 --OH.
The mole ratio of phosphate diester to phosphate monoester in the Gafac GB520 material is greater than 3 to 1.